Lanthanide-anion complexation of a new polyaminopolycarboxylate, DTTAP

Sawyer, Douglas J.; Powell, J.E.

doi:10.1016/s0277-5387(00)86256-7

Cited by 13 publications

(7 citation statements)

References 8 publications

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“…Table 1 compares the determined acid dissociation constants for HEDTTA with those reported for DTPA 35 and diethylenetriamine-N,N,N″,N″-tetraacetic-N′-propionic acid, DTTA-PA, determined by Sawyer and Powell. 36 The HEDTTA pK a values are similar to those reported for DTPA in 2.0 M (H + /Na + )ClO 4 . Nearly statistical agreement of all amine protonation sites of HEDTTA and DTPA indicates that pendant arm substitution has minimal inductive influence on the diethylenetriamine backbone.…”

Section: Resultssupporting

confidence: 77%

“…The acid dissociation reactions for HEDTTA are summarized by cumulative equilibria expression as described by eq . Table lists the acid dissociation constants for HEDTTA resolved in this study, together with p K a values previously determined at I = 2.0 M for DTPA and DTTA-PA for comparison. , The proton associated with the ethyl alcohol (p K a ≈ 16) is not readily dissociable in the p C H range typical of potentiometric titration; therefore, it was treated as an inert pendant arm for modeling purposes. The H 6 R 2+ and H 7 R 3+ species have weak proton association, and the acidic p K a values were not accessible using potentiometric titration methods due to the limitations of the glass electrode. …”

Section: Resultsmentioning

confidence: 99%

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Thermodynamic, Spectroscopic, and Computational Studies of f-Element Complexation by N-Hydroxyethyl-diethylenetriamine-N,N′,N″,N″-tetraacetic Acid

et al. 2017

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Potentiometric and spectroscopic techniques were combined with DFT calculations to probe the coordination environment and determine thermodynamic features of trivalent f-element complexation by N-hydroxyethyl-diethylenetriamine-N,N',N″,N″-tetraacetic acid, HEDTTA. Ligand protonation constants and lanthanide stability constants were determined using potentiometry. Five protonation constants were accessible in I = 2.0 M (H/Na)ClO. UV-vis spectroscopy was used to determine stability constants for Nd and Am complexation with HEDTTA. Luminescence spectroscopy indicates two water molecules in the inner coordination sphere of the Eu/HEDTTA complex, suggesting HEDTTA is heptadentate. Luminescence data was supported by DFT calculations, which demonstrate that substitution of the acetate pendant arm by a N-hydroxyethyl group weakens the metal-nitrogen bond. This bond elongation is reflected in HEDTTA's ability to differentiate trivalent actinides from trivalent lanthanides. The trans-lanthanide Ln/HEDTTA complex stability trend is analogous to Ln/DTPA complexation; however, the loss of one chelate ring resulting from structural substitution weakens the complexation by ∼3 orders of magnitude. Successful separation of trivalent americium from trivalent lanthanides was demonstrated when HEDTTA was utilized as aqueous holdback complexant in a liquid-liquid system. Time-dependent extraction studies for HEDTTA were compared to diethylenetriamine-N,N,N',N″,N″-pentaacetic acid (DTPA) and N-hydroxyethyl-ethylenediamine-N,N',N'-triacetic acid (HEDTA). The results indicate substantially enhanced phase-transfer kinetic rates for mixtures containing HEDTTA.

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Section: Resultssupporting

confidence: 77%

Section: Resultsmentioning

confidence: 99%

Thermodynamic, Spectroscopic, and Computational Studies of f-Element Complexation by N-Hydroxyethyl-diethylenetriamine-N,N′,N″,N″-tetraacetic Acid

et al. 2017

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“…However, these same structural modifications are also expected to decrease the thermodynamic stability of the resulting complexes because six-membered chelate rings are less stable than five-membered chelate rings [36,38]. This is nicely reflected by the measured stability constants of Gd 3+ complexes formed with a series of DTPA homologs (Chart 4.2): DTTA-prop(c) (the propionate sidearm is attached to the central N) (log K Gd(L) = 16.7), DTTA-prop(t) (the propionate sidearm is attached to one of the terminal N atoms) (log K Gd(L) = 19.7), EPTPA (log K Gd(L) = 18.75), p-NO 2 -Bn-EPTPA (log K Gd(L) = 19.2) and DPTPA (log K Gd(L) = 13.0) [35,37]. Interestingly, the effect of the propionate sidearm on the complex stability is less pronounced when it is located on one of the terminal nitrogens (DTTA-prop(c) vs. DTTA-prop(t)) [35].…”

Section: Stability Of Metal-ligand Complexesmentioning

confidence: 99%

Stability and Toxicity of Contrast Agents

Brücher

Tircsó

Baranyai

et al. 2013

The Chemistry of Contrast Agents in Medical Magnetic Resonance Imaging

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Magnetic Resonance Imaging (MRI) derives directly from the phenomenon of Nuclear Magnetic Resonance (NMR [1][2][3][4]), which is widely used by chemists to determine molecular structure. The word "nuclear" was dropped in the switch to imaging to avoid alarming patients as NMR has nothing to do with radioactivity. This book is intended mainly for chemists, who are generally familiar with the NMR spectra. After a brief overview of the technique explaining the notion of relaxation time and saturation transfer used in MRI, we will describe localization techniques, which are less well-known in chemistry. The purpose of this short chapter is not to provide a complete theory of MRI [5][6][7][8], but to understand the rest of the book concerning the action of contrast agents. We will not go into the theoretical background of the phenomena, and while it is important to have some understanding of quantum mechanics, it is not our purpose to develop this aspect. This is a "nuts and bolts" description of MRI. Whenever possible, we refer to chemists' knowledge of NMR (for example, "2D NMR"). Theoretical basis of NMR Short description of NMRIn most cases, MRI focuses on one type of atomic nucleus, that of hydrogen in H 2 O. We will therefore only use this nucleus, termed the " 1 H proton."The physical phenomenon of NMR lies at the boundary between "conventional" and "quantum" treatment due to the small transition energies involved. Traditionally, the 1 H proton can be considered as a charged

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“…For the Gd III complex of the DTPA derivative containing one propionate in a terminal position a stability constant of log K GdL 19.7 has been reported. [19] The thermodynamic stability constants alone are not sufficient to compare different complex stabilities under physiological conditions. The conditional stability constants, or more frequently the pM values are considered to be a better gauge of physiologically relevant complex stability.…”

Section: àmentioning

confidence: 99%

Gd^III Complexes with Fast Water Exchange and High Thermodynamic Stability: Potential Building Blocks for High‐Relaxivity MRI Contrast Agents

Laus

Ruloff

Tóth

et al. 2003

Chemistry A European J

162

176

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On the basis of structural considerations in the inner sphere of nine-coordinate, monohydrated Gd(III) poly(aminocarboxylate) complexes, we succeeded in accelerating the water exchange by inducing steric compression around the water binding site. We modified the common DTPA(5-) ligand (DTPA=(diethylenetriamine-N,N,N',N",N"-pentaacetic acid) by replacing one (EPTPA(5-)) or two (DPTPA(5-)) ethylene bridges of the backbone by propylene bridges, or one coordinating acetate by a propionate arm (DTTA-prop(5-)). The ligand EPTPA(5-) was additionally functionalized with a nitrobenzyl linker group (EPTPA-bz-NO(2) (5-)) to allow for coupling of the chelate to macromolecules. The water exchange rate, determined from a combined variable-temperature (17)O NMR and EPR study, is two orders of magnitude higher on [Gd(eptpa-bz-NO(2))(H(2)O)](2-) and [Gd(eptpa)(H(2)O)](2-) than on [Gd(dtpa)(H(2)O)](2-) (k(ex)298=150x10(6), 330x10(6), and 3.3x10(6) s(-1), respectively). This is optimal for attaining maximum proton relaxivities for Gd(III)-based, macrocyclic MRI contrast agents. The activation volume of the water exchange, measured by variable-pressure (17)O NMR spectroscopy, evidences a dissociative interchange mechanism for [Gd(eptpa)(H(2)O)](2-) (DeltaV(not equal sign)=(+6.6+/-1.0) cm(3) mol(-1)). In contrast to [Gd(eptpa)(H(2)O)](2-), an interchange mechanism is proved for the macrocyclic [Gd(trita)(H(2)O)](-) (DeltaV (not equal sign)=(-1.5+/-1.0) cm(3) mol(-1)), which has one more CH(2) group in the macrocycle than the commercial MRI contrast agent [Gd(dota)(H(2)O)](-), and for which the elongation of the amine backbone also resulted in a remarkably fast water exchange. When one acetate of DTPA(5-) is substituted by a propionate, the water exchange rate on the Gd(III) complex increases by a factor of 10 (k(ex)298=31x10(6) s(-1)). The [Gd(dptpa)](2-) chelate has no inner-sphere water molecule. The protonation constants of the EPTPA-bz-NO(2) (5-) and DPTPA(5-) ligands and the stability constants of their complexes with Gd(III), Zn(II), Cu(II) and Ca(II) were determined by pH potentiometry. Although the thermodynamic stability of [Gd(eptpa-bz-NO(2))(H(2)O)](2-) is reduced to a slight extent in comparison with [Gd(dtpa)(H(2)O)](2-), it is stable enough to be used in medical diagnostics as an MRI contrast agent. Therefore both this chelate and [Gd(trita)(H(2)O)](-) are potential building blocks for the development of high-relaxivity macromolecular agents.

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Lanthanide-anion complexation of a new polyaminopolycarboxylate, DTTAP

Cited by 13 publications

References 8 publications

Thermodynamic, Spectroscopic, and Computational Studies of f-Element Complexation by N-Hydroxyethyl-diethylenetriamine-N,N′,N″,N″-tetraacetic Acid

Thermodynamic, Spectroscopic, and Computational Studies of f-Element Complexation by N-Hydroxyethyl-diethylenetriamine-N,N′,N″,N″-tetraacetic Acid

Stability and Toxicity of Contrast Agents

Gd^III Complexes with Fast Water Exchange and High Thermodynamic Stability: Potential Building Blocks for High‐Relaxivity MRI Contrast Agents

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Lanthanide-anion complexation of a new polyaminopolycarboxylate, DTTAP

Cited by 13 publications

References 8 publications

Thermodynamic, Spectroscopic, and Computational Studies of f-Element Complexation by N-Hydroxyethyl-diethylenetriamine-N,N′,N″,N″-tetraacetic Acid

Thermodynamic, Spectroscopic, and Computational Studies of f-Element Complexation by N-Hydroxyethyl-diethylenetriamine-N,N′,N″,N″-tetraacetic Acid

Stability and Toxicity of Contrast Agents

GdIII Complexes with Fast Water Exchange and High Thermodynamic Stability: Potential Building Blocks for High‐Relaxivity MRI Contrast Agents

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Product

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Gd^III Complexes with Fast Water Exchange and High Thermodynamic Stability: Potential Building Blocks for High‐Relaxivity MRI Contrast Agents